Russia's Defense Ministry said the power of North Korea's nuclear test blast on Tuesday surpassed 7 kilotons, a ministry source told the Interfax-AVN military news agency.

South Korea said earlier on Tuesday that the size of the seismic activity indicated a nuclear explosion slightly larger than the North's two previous tests at 6-7 kilotons. The Hiroshima bomb was, by comparison, around 20 kilotons. (Reuters)